Report "I have a NuTone model 9965. Everything (light, exhaust fan, and heater fan) works but the heater does not. Power to the heater and heater fan works. I cleaned up all the insides of the unit of dust and checked all electrical connections, plugs and outlets. I don't see any evidence of electrical problems but I heard a pop and a small piece of debris on fire fell through the vent opening and to the floor when it broke. Any idea of what the problem is? Thanks, Neil"